Thermoplastic polyurethane compounds exhibiting enhanced stain resistance

ABSTRACT

Thermoplastic articles are molded from thermoplastic polyurethane compounds including blends of aliphatic poly-caprolactone thermoplastic polyurethane and aromatic thermoplastic polyurethane selected from aromatic polyester thermoplastic polyurethane, aromatic polyether thermoplastic polyurethane, and combinations thereof. The thermoplastic articles exhibit enhanced stain resistance, as represented by achieving a rating of 2 or better according to Blue Jean Abrasion Test, relative to thermoplastic articles molded from thermoplastic polyurethane compounds including either aromatic polyester thermoplastic polyurethane or aromatic polyether thermoplastic only, while also having good clarity (i.e., low haze) and other desirable properties. The thermoplastic articles can be especially useful as protective cases for handheld electronic devices.

CLAIM OF PRIORITY

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/790,319 bearing Attorney Docket Number 12019004and filed on Jan. 9, 2019, which is hereby incorporated by reference inits entirety.

FIELD OF THE INVENTION

This invention relates to thermoplastic polyurethane compounds andthermoplastic articles formed therefrom that have enhanced resistance toabrasion and staining while also exhibiting good clarity and otherdesirable properties.

BACKGROUND OF THE INVENTION

Demand exists for polymeric materials that are useful for makingprotective cases and other components or accessories for personalelectronic devices such as smart phones, tablets, and handheldcomputers.

Protective cases for personal electronic devices typically require goodaesthetics such as “look” and “feel” that are desirable to consumers.For example, some consumers prefer the look of protective cases that arerelatively clear in appearance or that are lightly or brightly colored.Further, some consumers prefer the feel of protective cases that arerelative soft to the touch without being sticky or tacky.

Thermoplastic elastomers (TPE), which are polymeric materials thatexhibit elasticity while remaining thermoplastic, can be useful formaking protective cases for personal electronic devices. TPEs caninclude styrenic block copolymers (SBC), thermoplastic vulcanizates(TPV), thermoplastic polyolefins (TPO), copolyesters (COPE),thermoplastic polyurethanes (TPU), copolyamides (COPA), olefinic blockcopolymers (OBC). Although certain TPEs, such as conventional TPUs, canoffer good clarity and other properties desirable for making protectivecases for personal electronic devices, drawbacks still exist.

For example, protective cases made from conventional TPUs can sufferfrom poor resistance to abrasion and staining when personal electronicdevices are placed by users in garments or clothing articles made fromdenim or other dyed fabrics, such as in a pocket of blue jeans.Disadvantageously, it is possible for such protective cases to beabraded by the fabric and stained by dye that transfers from the fabric.Such abrasion and staining is especially problematic when protectivecases are clear or lightly or brightly colored.

SUMMARY OF THE INVENTION

Consequently, a need exists for thermoplastic polyurethane compounds andthermoplastic articles molded therefrom that have enhanced resistance toabrasion and staining while also exhibiting good clarity and otherdesirable properties.

The aforementioned needs are met by one or more aspects of the presentinvention.

Surprisingly, it has been found that, by selecting blends of aliphaticpolycaprolactone thermoplastic polyurethane and aromatic thermoplasticpolyurethane selected from aromatic polyester thermoplasticpolyurethane, aromatic polyether thermoplastic polyurethane, andcombinations thereof, it is possible to provide thermoplasticpolyurethane compounds and thermoplastic articles formed therefromhaving enhanced resistance to abrasion and staining while alsoexhibiting good clarity and other desirable properties.

Some aspects of the invention are directed to thermoplastic polyurethanecompounds including blends of aliphatic polycaprolactone thermoplasticpolyurethane and aromatic thermoplastic polyurethane selected fromaromatic polyester thermoplastic polyurethane, aromatic polyetherthermoplastic polyurethane, and combinations thereof, wherein from about10 to about 50 parts by weight is the aliphatic polycaprolactonethermoplastic polyurethane and from about 50 to about 90 parts by weightis the aromatic thermoplastic polyurethane.

Other aspects of the invention are directed to thermoplastic articlesmolded from thermoplastic polyurethane compounds including blends ofaliphatic polycaprolactone thermoplastic polyurethane and aromaticthermoplastic polyurethane selected from aromatic polyesterthermoplastic polyurethane, aromatic polyether thermoplasticpolyurethane, and combinations thereof.

Further aspects of the invention are directed to methods of makingthermoplastic articles. The methods include steps of providingthermoplastic polyurethane compounds as described herein, and moldingthe thermoplastic polyurethane compounds to provide the thermoplasticarticles.

Even further aspects of the invention are directed to methods ofimproving resistance to Blue Jean Staining for thermoplastic articlesmolded from thermoplastic polyurethane compounds. The methods include astep of selecting blends of aliphatic polycaprolactone thermoplasticpolyurethane and aromatic thermoplastic polyurethane selected fromaromatic polyester thermoplastic polyurethane, aromatic polyetherthermoplastic polyurethane, and combinations thereof, to provide thethermoplastic polyurethane compounds as described herein to form thethermoplastic articles as described herein.

Features of the invention will become apparent with reference to thefollowing embodiments. There exist various refinements of the featuresnoted in relation to the above-mentioned aspects of the disclosedinvention. Additional features may also be incorporated in theabove-mentioned aspects of the disclosed invention. These refinementsand additional features may exist individually or in any combination.For instance, various features discussed below in relation to any of thedescribed aspects of the invention may be incorporated into any of thedescribed aspects of the invention alone or in any combination.

EMBODIMENTS OF THE INVENTION

In some embodiments, the invention is directed to thermoplasticpolyurethane compounds. In other embodiments, the invention is directedto thermoplastic articles molded from thermoplastic polyurethanecompounds. In further embodiments, the invention is directed to methodsof making thermoplastic articles. In even further embodiments, theinvention is directed to methods of improving resistance to Blue JeanStaining for thermoplastic articles molded from thermoplasticpolyurethane compounds. Required and optional features of these andother embodiments of the disclosed invention are described.

As used herein, “aliphatic polycaprolactone thermoplastic polyurethane”means a type of thermoplastic polyurethane that is a reaction product ofreactants including a polycaprolactone polyol and an aliphaticdiisocyanate and, optionally, chain extender.

As used herein, “aliphatic polyester thermoplastic polyurethane” means atype of thermoplastic polyurethane that is a reaction product ofreactants including a polyester polyol (other than polycaprolactonepolyol) and an aliphatic diisocyanate and, optionally, chain extender.

As used herein, “aliphatic polyether thermoplastic polyurethane” means atype of thermoplastic polyurethane that is a reaction product ofreactants including a polyether polyol and an aliphatic diisocyanateand, optionally, chain extender.

As used herein, “aromatic polycaprolactone thermoplastic polyurethane”means a type of thermoplastic polyurethane that is a reaction product ofreactants including a polycaprolactone polyol and an aromaticdiisocyanate and, optionally, chain extender.

As used herein, “aromatic polyester thermoplastic polyurethane” means atype of thermoplastic polyurethane that is a reaction product ofreactants including a polyester polyol (other than polycaprolactonepolyol) and an aromatic diisocyanate and, optionally, chain extender.

As used herein, “aromatic polyether thermoplastic polyurethane” means atype of thermoplastic polyurethane that is a reaction product ofreactants including a polyether polyol and an aromatic diisocyanate and,optionally, chain extender.

As used herein, the term “Blue Jean Abrasion Test” means the FordLaboratory Test Method (FLTM) BN 107-01 Crocking Test as performed withequipment, set-up, materials, and conditions as follows:

-   -   Instrument: TABER Linear Abraser-Model 5750;    -   Accessory: TABER Crockmeter Attachment with 16 mm Acrylic        Finger;    -   Abradant: LEVI'S 505 Regular Cut Blue Jeans (circular cloth cut        with shears from the lower part of the jean leg and positioned        on the finger of the Crockmeter such that the weave is oblique        to the direction of rubbing and affixed on the finger with a        retaining clip);    -   Stroke Length: 4 inches (100 mm);    -   Cycle Speed: 60 cycles per minute;    -   Load: 9 Newtons (918 grams); and    -   Conditions: Temperature of 76° F. (24.4° C.) and Relative        Humidity of 47% (with test specimens conditioned at least 24        hours);    -   Ratings: 1=No Blue Jean Staining after both 100 cycles and 500        cycles; 2=No Blue Jean Staining after 100 cycles but Blue Jean        Staining after 500 cycles; 3=Blue Jean Staining after both 100        cycles and 500 cycles.

As used herein, the term “Blue Jean Staining” means abrasion ordiscoloration from color transfer visually observable on a testspecimen, such as a thermoplastic article, after subjecting the testspecimen to the Blue Jean Abrasion Test.

As used herein, “clarity” means a qualitative determination made byvisually observing and comparing a specimen plaque molded at a thicknessof 1.5 mm from a specimen thermoplastic polyurethane compound against acontrol plaque molded at a thickness of 1.5 mm from neat IROGRAN A 85 P4394 UV aliphatic polycaprolactone thermoplastic polyurethane availablefrom Huntsman. Ratings are assigned according to the following criteria:1=specimen is comparable in clarity relative to the control; 2=specimenis hazy relative to the control; 3=specimen is opaque relative to thecontrol.

As used herein, the term “compound” means a composition or mixtureresulting from melt mixing, or compounding, a neat polymer and at leastone other ingredient including but not limited to one or more additives,or one or more other polymers, or both.

As used herein, “Delta E” means a perceived color difference within theCIELAB color space and under D65 illuminant as measured according toASTM E1347-6 using a COLOR EYE 7000A instrument available from Macbeth(X-Rite).

As used herein, “haze” is a measure of loss of clarity as measuredaccording to ASTM D1003. Clarity also can be assessed qualitatively byvisual observation.

As used herein, the term “free of” a certain component or substancemeans, in some embodiments, that no amount of that component orsubstance is intentionally present, and, in other embodiments, that nofunctionally effective amount of that component or substance is present,and, in further embodiments, that no amount of that component orsubstance is present.

As used herein, the term “molded from” means, with respect to an article(or component of an article) and a material, that the article (orcomponent of the article) is molded, extruded, shaped, formed, orotherwise made from the material. As such, the term “molded from” means,in some embodiments, the article (or component of an article) cancomprise, consist essentially of, or consist of, the material; and, inother embodiments, the article (or component of an article) consists ofthe material because the article (or component of an article) is, forexample, made by an injection molding process.

As used herein, the term “QUV Test” means an accelerated weathering testas performed according to ASTM E1347-06 with equipment and conditions asfollows:

-   -   Equipment: QUV/Spray Accelerated Weathering Tester available        from Q-Lab;    -   UV Irradiance: 0.68 W/m²;    -   Temperature: 45° C.; and    -   Duration: 14 days.

As used herein, the term “visually observable” (including “visualobservation” and other like terms) means observable (or an observationmade) by an unaided human eye under common interior lighting conditionsat a distance no greater than 50 centimeters from the unaided human eye.

As used herein, the term “Yellow Index” means a rating of yellownessmeasured according to ASTM E313 using a COLOR EYE 7000A instrumentavailable from Macbeth (X-Rite).

Thermoplastic Polyurethane Compounds and Molded Articles

Some aspects of the invention are directed to thermoplastic polyurethanecompounds. Other aspects of the invention are directed to thermoplasticarticles molded from the thermoplastic polyurethane compounds.

According to the invention, thermoplastic polyurethane compounds includeblends of aliphatic polycaprolactone thermoplastic polyurethane andaromatic thermoplastic polyurethane selected from aromatic polyesterthermoplastic polyurethane, aromatic polyether thermoplasticpolyurethane, and combinations thereof, wherein from about 10 to about50 parts by weight is the aliphatic polycaprolactone thermoplasticpolyurethane and from about 50 to about 90 parts by weight is thearomatic thermoplastic polyurethane. Additionally, the thermoplasticpolyurethane compounds are free of aromatic polycaprolactonethermoplastic polyurethane. The thermoplastic articles molded therefromcan achieve a rating of 2 or better according to Blue Jean AbrasionTest.

Surprisingly, it has been found that it is possible to improveresistance to Blue Jean Staining for a thermoplastic article molded froma thermoplastic polyurethane compound when the thermoplasticpolyurethane compound includes thermoplastic polyurethane selected fromblends of aliphatic polycaprolactone thermoplastic polyurethane andaromatic thermoplastic polyurethane selected from aromatic polyesterthermoplastic polyurethane, aromatic polyether thermoplasticpolyurethane, and combinations thereof.

In some embodiments, the thermoplastic polyurethane is selected fromblends of aliphatic polycaprolactone thermoplastic polyurethane andaromatic thermoplastic polyurethane selected from aromatic polyesterthermoplastic polyurethane, aromatic polyether thermoplasticpolyurethane, and combinations thereof, wherein from about 25 to about50 parts by weight is the aromatic polycaprolactone thermoplasticpolyurethane and from about 50 to about 75 parts by weight is the otheraromatic thermoplastic polyurethane, and wherein the thermoplasticarticle achieves a rating of 1 according to Blue Jean Abrasion Test.

In some embodiments, the thermoplastic polyurethane compounds furtherinclude additives selected from antioxidants and stabilizers; colorants;mold release agents; processing aids; ultraviolet light absorbers; andcombinations thereof.

In some embodiments, the thermoplastic polyurethane compounds furtherinclude secondary polymer selected from styrenic block copolymers,thermoplastic vulcanizates, polyolefin elastomers, copolyesters, andcombinations thereof.

In some embodiments, the thermoplastic polyurethane compound furtherincludes plasticizer.

In some embodiments, the thermoplastic polyurethane compounds are freeof aliphatic polyester thermoplastic polyurethane, aliphatic polyetherthermoplastic, and combinations thereof.

In some embodiments, the thermoplastic polyurethane compounds includefrom about 0.1 to about 2 parts by weight of ultraviolet light absorber,and the thermoplastic articles molded therefrom, after subjected to QUVTest, achieves a Delta E of less than about 4.5 and a Yellow Index ofless than about 6.5.

In other embodiments, the thermoplastic articles, after subjected to QUVTest, can achieve a Delta E of less than about 3.5, or less than about3.0, or less than about 2.0.

In further embodiments, the thermoplastic articles, after subjected toQUV Test, can achieve a Yellow Index of less than about 5.0, or lessthan about 3.5, or less than about 2.5.

Blends of Thermoplastic Polyurethanes

In general, thermoplastic polyurethanes (TPUs) are block copolymerscomposed of hard segments and soft segments. The hard segment is builtfrom the reaction of an isocyanate and a chain extender or short-chaindiol. The soft segment is built from the reaction of an isocyanate and apolyol or long-chain diol. TPUs can be categorized into two groups basedon the chemistry of the isocyanate component: (1) aromatic, and (2)aliphatic. Additionally, TPUs can be classified into three classes basedon the chemistry of the soft segment: (1) polyester, (2) polyether, and(3) polycaprolactone.

According to the invention, thermoplastic polyurethane compounds includeblends of aliphatic polycaprolactone thermoplastic polyurethane andaromatic thermoplastic polyurethane selected from aromatic polyesterthermoplastic polyurethane, aromatic polyether thermoplasticpolyurethane, and combinations thereof.

Suitable aliphatic polycaprolactone thermoplastic polyurethanes includeconventional or commercially available aliphatic polycaprolactonethermoplastic polyurethanes. A single commercial grade of aliphaticpolycaprolactone thermoplastic polyurethane or a combination of two ormore different commercial grades of aliphatic polycaprolactonethermoplastic polyurethane can be used as the aliphatic polycaprolactonethermoplastic polyurethane in the disclosed invention.

Non-limiting examples of commercially available aliphaticpolycaprolactone thermoplastic polyurethanes include those under theKRYSTALGRAN brand, such as grade PN03-221, available from Huntsman, andthose under the ESTANE brand, such as grades 2102-90A and 2102-55D,available from Lubrizol.

Suitable aromatic polyester thermoplastic polyurethanes includeconventional or commercially available aromatic polyester thermoplasticpolyurethanes. A single commercial grade of aromatic polyesterthermoplastic polyurethane or a combination of two or more differentcommercial grades of aromatic polyester thermoplastic polyurethane canbe used as the aromatic polyester thermoplastic polyurethane in thedisclosed invention.

Non-limiting examples of commercially available aromatic polyesterthermoplastic polyurethanes include those under the ELASTOLLAN brand,such as grade S85A55N, available from BASF.

Suitable aromatic polyether thermoplastic polyurethanes includeconventional or commercially available aromatic polyether thermoplasticpolyurethanes. A single commercial grade of aromatic polyetherthermoplastic polyurethane or a combination of two or more differentcommercial grades of aromatic polyether thermoplastic polyurethane canbe used as the aromatic polyether thermoplastic polyurethane in thedisclosed invention.

Non-limiting examples of commercially available aromatic polyetherthermoplastic polyurethanes include those under the IRGOGRAN brand, suchas grade A 85 P 4394 UV, available from Huntsman.

Optional Additives

In some embodiments, the thermoplastic polyurethane compounds furtherinclude one or more optional additives.

Suitable optional additives include conventional or commerciallyavailable plastics additives. Those skilled in the art of thermoplasticscompounding, without undue experimentation, can select suitableadditives from available references, for example, E. W. Flick, “PlasticsAdditives Database,” Plastics Design Library (Elsevier 2004).

Optional additives can be used in any amount that is sufficient toobtain a desired processing or performance property for thethermoplastic polyurethane compound and/or the thermoplastic articlemolded therefrom. The amount should not be wasteful of the additive nordetrimental to the processing or performance of the thermoplasticpolyurethane compound and/or the thermoplastic article molded therefrom.

Non-limiting examples of optional additives include adhesion promoters;anti-fogging agents; antioxidants; anti-static agents; biocides(antibacterials, fungicides, and mildewcides); colorants includingpigments and dyes; dispersants; fillers and extenders; fire and flameretardants and smoke suppressants; hardness adjusters; impact modifiers;initiators; lubricants; micas; mold release agents; oils andplasticizers; processing aids; secondary polymers; silanes, titanatesand zirconates; slip and anti-blocking agents; stabilizers; stearates;ultraviolet light absorbers; viscosity regulators; and waxes.

In some embodiments, the thermoplastic polyurethane compounds furtherinclude one or more of antioxidants and stabilizers; colorants; moldrelease agents; ultraviolet light absorbers; and combinations thereof.

Optional Secondary Polymer

In some embodiments, the thermoplastic polyurethane compounds furtherinclude secondary polymer (i.e., polymer resin other than thethermoplastic polyurethane component).

Secondary polymer should be compatible with the thermoplasticpolyurethane and can, for example, contribute to improved processabilityor desirable physical properties, such as hardness, in the thermoplasticpolyurethane compound.

Suitable secondary polymer includes thermoplastic elastomers other thanthermoplastic polyurethanes, such as styrenic block copolymers,thermoplastic vulcanizates, polyolefin elastomers, copolyesters, andcombinations thereof.

Non-limiting examples of suitable styrenic block copolymers includestyrene-ethylene/butylene-styrene (SEBS),styrene-ethylene/propylene-styrene (SEPS),styrene-ethylene/ethylene/propylene-styrene (SEEPS),styrene-isobutylene-styrene (SIBS), styrene-butadiene-styrene (SBS),styrene-isoprene-styrene (SIS), and combinations thereof.

Non-limiting examples of suitable thermoplastic vulcanizate (TPV)include blends of a continuous phase of a polyolefin such aspolypropylene and a discontinuous phase of a vulcanized rubber such ascrosslinked EPDM.

Non-limiting examples of suitable polyolefin elastomer includepropylene-based elastomers, ethylene/α-olefin random copolymers, andcombinations thereof.

Non-limiting examples of suitable copolyesters include block copolymerscomposed from repeating soft segments of aliphatic polyether oraliphatic polyester and hard segments of aromatic polyester.

Optional Plasticizer

In some embodiments, especially when thermoplastic elastomer other thanthermoplastic polyurethane is included as secondary polymer, thethermoplastic polyurethane compounds further include plasticizer.

Plasticizer can be used, for example, to adjust softness and/or improveflow or other properties of the thermoplastic polyurethane compound.

Any conventional oil capable of plasticizing styrenic block copolymer,such as mineral oil, vegetable oil, synthetic oil, etc., can be used inthe present invention. Examples of commercially available oils includethose available under the PURETOL 380 brand from Petro-Canada, and thoseavailable under the PRIMOL 382 brand from ExxonMobil.

Ranges of Ingredients in the TPU Compounds

Table 1 below shows ranges of ingredients, in parts by weight, which canbe acceptable, desirable, and preferable for some embodiments ofthermoplastic polyurethane (TPU) compounds of the disclosed invention.Other possible ranges of ingredients for other embodiments of thedisclosed invention are as described elsewhere herein.

Thermoplastic polyurethane compounds, in some embodiments, can comprise,consist essentially of, or consist of these ingredients. Any numberbetween the ends of the ranges is also contemplated as an end of arange, such that all possible combinations are contemplated within thepossibilities of Table 1 as embodiments of compounds for use in thedisclosed invention. Unless expressly stated otherwise herein, anydisclosed number is intended to refer to both exactly the disclosednumber and “about” the disclosed number, such that either possibility iscontemplated within the possibilities of Table 1 as embodiments ofcompounds for use in the disclosed invention.

TABLE 1 Thermoplastic Polyurethane Compounds (Parts by Weight)Ingredient Acceptable Desirable Preferable Aliphatic PolycaprolactoneTPU 10-50 25-50 35-50 Aromatic TPU 50-90 50-75 50-65 Optional Additives 0-20 0.1-10  0.5-5  Optional Secondary Polymer  0-200  0-150  0-100Optional Plasticizer  0-400  0-300  0-200

Processing and Methods of Making

Preparation of thermoplastic polyurethane compounds of the disclosedinvention is uncomplicated once the proper ingredients have beenselected. The compound can be made in batch or continuous operations.

Mixing in a continuous process typically occurs in an extruder that iselevated to a temperature that is sufficient to melt the polymer matrixwith addition of all additives at the feed-throat, or by injection orside-feeders downstream. Extruder speeds can range from about 200 toabout 700 revolutions per minute (rpm), for example, from about 250 rpmto about 350 rpm. Typically, the output from the extruder is pelletizedfor later processing into thermoplastic articles.

Subsequent preparation of thermoplastic articles of the disclosedinvention also is uncomplicated once thermoplastic polyurethanecompounds of the present invention are provided. For example,thermoplastic articles of the present invention can be made by injectionmolding, extrusion, blow molding, rotational molding, thermoforming,calendering, and the like.

Processing techniques are described in available references, forexample, Dominick V. Rosato et al., Plastics Design Handbook (Springer2013).

In some embodiments, thermoplastic elastomer compounds of the disclosedinvention are molded by injection molding processes into thermoplasticarticles.

Further aspects of the invention are directed to overmolded articlesmade by overmolding processes.

According to the invention, the overmolded articles include (a) anovermold portion including the thermoplastic article of any embodimentsof the disclosed invention, and (b) a substrate portion molded from athermoplastic resin compound. The overmold portion is bonded onto thesubstrate portion at a bond interface, and the bond interface is free ofadhesive. The thermoplastic resin compound includes a thermoplasticresin and optionally additives. Non-limiting examples of suitablethermoplastic resins include polyamides, polycarbonates (PC),acrylonitrile butadiene styrene (ABS), polycarbonate/acrylonitrilebutadiene styrene (PC/ABS), styrene-acrylonitrile (SAN), and the like.

Methods of Improving Resistance to Blue Jean Staining

Some aspects of the invention are directed to methods of improvingresistance to Blue Jean Staining for thermoplastic articles molded fromthermoplastic polyurethane compounds. The methods include a step ofselecting blends of aliphatic polycaprolactone thermoplasticpolyurethane and aromatic thermoplastic polyurethane selected fromaromatic polyester thermoplastic polyurethane, aromatic polyetherthermoplastic polyurethane, and combinations thereof, wherein from about10 to about 50 parts by weight is the aliphatic polycaprolactonethermoplastic polyurethane and from about 50 to about 90 parts by weightis the aromatic thermoplastic polyurethane. Additionally, thethermoplastic polyurethane compounds are free of aromaticpolycaprolactone thermoplastic polyurethane. The thermoplastic articlesmolded therefrom can achieve a rating of 2 or better according to BlueJean Abrasion Test.

In some embodiments, the methods include providing the thermoplasticpolyurethane compounds of any embodiments of the disclosed invention. Inother embodiments, the methods include molding the thermoplasticarticles from the thermoplastic polyurethane compounds of anyembodiments of the disclosed invention.

Usefulness of the Invention

Thermoplastic polyurethane compounds of the disclosed invention can beuseful for making any type of thermoplastic article, or anythermoplastic component of a multi-component article or device, forwhich properties such as enhanced resistance to abrasion and stainingand good clarity are desirable or required.

Thermoplastic polyurethane compounds of the disclosed invention havepotential for use in applications in many different industries,including but not limited to: automotive and transportation; consumerproducts; electronics; healthcare and medical; household appliances; andother industries or applications benefiting from the unique combinationof properties.

In some embodiments, thermoplastic polyurethane compounds of the presentinvention can be especially useful for making protective cases forpersonal electronic devices such as smart phones or other devices that auser frequently places into and removes from a garment or clothingarticle made from denim or other dyed fabric, such as a pocket of bluejeans.

Some aspects of the invention are directed to electronic devicesincluding the thermoplastic articles as described herein.

Other aspects of the invention are directed to accessories for anelectronic device wherein the accessories include the thermoplasticarticles as disclosed herein. In some embodiments, the accessory is aprotective case for a handheld electronic device.

Examples

Non-limiting examples of thermoplastic polyurethane compounds of variousembodiments of the disclosed invention are provided.

Table 2 below identifies ingredients and their sources for thethermoplastic polyurethane compounds of the Examples.

TABLE 2 Ingredient Description Brand Source Aromatic polyester TPUELASTOLLAN S85A55N BASF Aromatic polyether TPU IROGRAN A 85 P 4394 UVHuntsman Aliphatic polycaprolactone KRYSTALGRAN PN03-221 Huntsman TPUUltraviolet light absorber TINUVIN 234 BASF Ultraviolet light absorberTINUVIN 622 BASF Mold release wax KEMAMIDE B PMC Biogenix AntioxidantIRGASTAB FS301 BASF Antioxidant IRGANOX 1010 BASF

To prepare the Examples, the ingredients all together were compoundedand extruded as pellets on a twin screw extruder at 196° C. and 300 rpm.Subsequently, the extruded pellets were injection molded (barreltemperature at 205° C. and molder temperature at 25° C.) into specimenplaques having dimensions of 150×125×1.5 mm and evaluated for thereported properties.

Table 3 below shows the formulations and certain properties ofComparative Example A and Examples 1 to 3.

TABLE 3 Example A 1 2 3 Wt. Parts Ingredients ELASTOLLAN S85A55N 100 8570 60 IROGRAN A 85 P 4394 UV — — — — KRYSTALGRAN PN03-221 — 15 30 40KEMAMIDE B 0.1 0.1 0.1 0.1 IRGANOX 1010 0.2 0.2 0.2 0.2 TOTAL 100.3100.3 100.3 100.3 Properties Hardness (Shore A) 82 81 77 75 Blue JeanAbrasion Test 3 2 1 1 Clarity (Visual Observation) 1 1 1 1 QUV Test,Delta E — — — — QUV Test, Yellow Index — — — —

Table 4 below shows the formulations and certain properties ofComparative Example B and Examples 4 to 6.

TABLE 4 Example B 4 5 6 Wt. Parts Ingredients ELASTOLLAN S85A55N — — — —IROGRAN A 85 P 4394 UV 100 85 70 60 KRYSTALGRAN PN03-221 — 15 30 40KEMAMIDE B 0.1 0.1 0.1 0.1 IRGANOX 1010 0.2 0.2 0.2 0.2 TOTAL 100.3100.3 100.3 100.3 Properties Hardness (Shore A) 82 78 74 70 Blue JeanAbrasion Test 3 2 1 1 Clarity (Visual Observation) 1 1 1 1 QUV Test,Delta E — — — — QUV Test, Yellow Index — — — —

Table 5 below shows the formulations and certain properties ofComparative Examples C to D and Examples 7 to 10.

TABLE 5 Example C D 7 8 9 10 Wt. Parts Ingredients ELASTOLLAN S85A55N100 95 90 85 80 75 KRYSTALGRAN PN03-221 — 5 10 15 20 25 TINUVIN 234 0.60.6 0.6 0.6 0.6 0.6 TINUVIN 622 0.3 0.3 0.3 0.3 0.3 0.3 KEMAMIDE B 0.10.1 0.1 0.1 0.1 0.1 IRGASTAB FS301 0.15 0.15 0.15 0.15 0.15 0.15 TOTAL101.15 101.15 101.15 101.15 101.15 101.15 Properties Hardness (Shore A)81 81 80 80 80 80 Blue Jean Abrasion Test — — — — — — Clarity (VisualObservation) 1 1 1 1 1 1 QUV Test, Delta E 12.5 5.3 4.1 3.1 2.1 1.5 QUVTest, Yellow Index 18.1 7.7 6.2 4.7 3.2 2.2

Table 6 below shows the formulations and certain properties ofComparative Examples E to F and Examples 11 to 14.

TABLE 5 Example E F 11 12 13 14 Wt. Parts Ingredients ELASTOLLAN S85A55N100 95 90 85 80 75 KRYSTALGRAN PN03-221 — 5 10 15 20 25 TINUVIN 234 — —— — — — TINUVIN 622 — — — — — — KEMAMIDE B 0.1 0.1 0.1 0.1 0.1 0.1IRGASTAB FS301 0.15 0.15 0.15 0.15 0.15 0.15 TOTAL 100.25 100.25 100.25100.25 100.25 100.25 Properties Hardness (Shore A) 81 81 80 80 80 80Blue Jean Abrasion Test — — — — — — Clarity (Visual Observation) 1 1 1 11 1 QUV Test, Delta E 31.1 23.6 20.1 16.5 13.2 9.8 QUV Test, YellowIndex 44.6 34.7 29.6 24.6 20.9 14.9

Without undue experimentation, those having ordinary skill in the artcan utilize the written description, including the Examples, to make anduse aspects of the disclosed invention.

All documents cited in the Embodiments of the Invention are incorporatedherein by reference in their entirety unless otherwise specified. Thecitation of any document is not to be construed as an admission that itis prior art with respect to the disclosed invention.

While particular embodiments of the disclosed invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. The appendedclaims are intended to cover all such changes and modifications withinthe scope of the disclosed invention.

What is claimed is:
 1. A thermoplastic article molded from athermoplastic polyurethane compound, the thermoplastic polyurethanecompound comprising: 100 parts by weight of thermoplastic polyurethaneselected from blends of aliphatic polycaprolactone thermoplasticpolyurethane and aromatic thermoplastic polyurethane selected fromaromatic polyester thermoplastic polyurethane, aromatic polyetherthermoplastic polyurethane, and combinations thereof, wherein from about10 to about 50 parts by weight is the aliphatic polycaprolactonethermoplastic polyurethane and from about 50 to about 90 parts by weightis the aromatic thermoplastic polyurethane; wherein the thermoplasticpolyurethane compound is free of aromatic polycaprolactone thermoplasticpolyurethane; and wherein the thermoplastic article achieves a rating of2 or better according to Blue Jean Abrasion Test.
 2. The thermoplasticarticle of claim 1, wherein from about 25 to about 50 parts by weight isthe aromatic polycaprolactone thermoplastic polyurethane and from about50 to about 75 parts by weight is the other aromatic thermoplasticpolyurethane, and wherein the thermoplastic article achieves a rating of1 according to Blue Jean Abrasion Test.
 3. The thermoplastic article ofclaim 1, wherein the thermoplastic polyurethane compound furthercomprises additives selected from antioxidants and stabilisers;colorants; mold release agents; processing aids; ultraviolet lightabsorbers; and combinations thereof.
 4. The thermoplastic article ofclaim 1, wherein the thermoplastic polyurethane compound furthercomprises secondary polymer selected from styrenic block copolymers,thermoplastic vulcanizates, polyolefin elastomers, copolyesters, andcombinations thereof.
 5. The thermoplastic article of claim 4, whereinthe thermoplastic polyurethane compound further comprises plasticizer.6. The thermoplastic article of claim 1, wherein the thermoplasticpolyurethane compound is free of aliphatic polyester thermoplasticpolyurethane and aliphatic polyether thermoplastic polyurethane.
 7. Thethermoplastic article of claim 1: wherein the thermoplastic polyurethanecompound further comprises from about 0.1 to about 2 parts by weight ofultraviolet light absorber; and wherein the thermoplastic article, aftersubjected to QUV Test, achieves a Delta E of less than about 4.5 and aYellow Index of less than about 6.5.
 8. An accessory for an electronicdevice, the accessory comprising the thermoplastic article of claim 1.9. The accessory of claim 8, wherein the accessory is a protective casefor a handheld electronic device.
 10. An overmolded article comprising:(a) overmold portion comprising the thermoplastic article of claim 1;and (b) a substrate portion molded from a thermoplastic resin compound;wherein the overmold portion is bonded onto the substrate portion at abond interface, and the bond interface is free of adhesive.
 11. A methodof improving resistance to Blue Jean Staining for a thermoplasticarticle molded from a thermoplastic polyurethane compound comprising 100parts by weight of thermoplastic polyurethane, the method comprising thestep of: selecting the thermoplastic polyurethane from blends ofaliphatic polycaprolactone thermoplastic polyurethane and aromaticthermoplastic polyurethane selected from aromatic polyesterthermoplastic polyurethane, aromatic polyether thermoplasticpolyurethane, and combinations thereof, wherein from about 10 to about50 parts by weight is the aliphatic polycaprolactone thermoplasticpolyurethane and from about 50 to about 90 parts by weight is thearomatic thermoplastic polyurethane; wherein the thermoplasticpolyurethane compound is free of aromatic polycaprolactone thermoplasticpolyurethane; and wherein the thermoplastic article achieves a rating of2 or better according to Blue Jean Abrasion Test.
 12. The method ofclaim 11, wherein from about 25 to about 50 parts by weight is thearomatic polycaprolactone thermoplastic polyurethane and from about 50to about 75 parts by weight is the other aromatic thermoplasticpolyurethane, and wherein the thermoplastic article achieves a rating of1 according to Blue Jean Abrasion Test.
 13. The method of claim 11,wherein the thermoplastic polyurethane compound is free of aliphaticpolyester thermoplastic polyurethane and aliphatic polyetherthermoplastic polyurethane.
 14. The method of claim 11, wherein thethermoplastic article is an accessory or portion thereof for anelectronic device.
 15. The method of claim 11, wherein the thermoplasticarticle is a protective case or portion thereof for a handheldelectronic device.